Pfizer Inc and BioNTech SE said on Monday (Sept 20) their Covid-19 vaccine induced a robust immune response in five to 11 year olds, and they plan to ask for regulatory authorization as soon as possible to use the shot in children in that age range in the United States, Europe and elsewhere.
The companies said their two-dose vaccine generated an immune response in the five-to-11 year olds in a Phase II/III clinical trial that matched what was previously observed in 16-to-25 year olds. The safety profile was also generally comparable to the older age group, they added.
"Since July, pediatric cases of Covid-19 have risen by about 240 per cent in the US - underscoring the public health need for vaccination," Pfizer Chief Executive Albert Bourla said in a news release.
"These trial results provide a strong foundation for seeking authorization of our vaccine for children five to 11 years old, and we plan to submit them to the FDA and other regulators with urgency," Bourla added.
The Pfizer/BioNTech vaccine already has won US regulatory authorisation for people age 12 and up, including full Food and Drug Administration approval last month for ages 16 and up.
Top US health officials believe regulators could make a decision on whether the shot is safe and effective in younger children within three weeks of the companies submitting a request for authorisation, two sources told Reuters this month.
A rapid authorisation could help mitigate a potential surge of cases this fall, with schools already open nationwide.
Covid-19 hospitalisations and deaths have surged in the United States in recent months due to the highly contagious Delta variant, especially in areas with low vaccination rates even as President Joe Biden implores vaccine holdouts to get their shots.
Pediatric cases are also up, particularly as children under 12 are all unvaccinated, but there is no indication that, beyond being more transmissible, the Delta virus is more dangerous in kids.
FDA acting Commissioner Janet Woodcock said that once the agency receives the application, its process for determining if the vaccine is safe and effective for children in the younger age group includes verifying the manufacturing processes for the lower concentrations of the shots and any study of its safety.
"We'll look at the clinical data and make sure that children responded to the vaccine the way we would expect," Woodcock said during an appearance on former Biden administration official Andy Slavitt's podcast.
Pfizer shares fell 1.3 per cent to $43.28 (S$58.45) before the bell on Monday amid broader market weakness.
The Pfizer/BioNTech vaccine, called Comirnaty, is authorized for use in children as young as 12 in many countries in addition to the United States. It was originally authorized for emergency use in people 16 or older in the United States in December 2020.
The five-to-11 year olds were given two shots of a 10-microgram dose of the vaccine, a third the dose size given to people 12 and older.
In addition, the companies said they expect data on how well the vaccine works in children ages two-to-five years and children ages six months-to-two years as soon as the fourth quarter of this year.
Unlike the larger clinical trial that the drug makers previously conducted in adults, the 2,268-participant pediatric trial was not primarily designed to measure the vaccine's efficacy by comparing the number of Covid-19 cases in vaccine recipients to those who received a placebo.
Instead, it compares the amount of neutralizing antibodies induced by the vaccine in the children to the response of older recipients in the adult trial.
A Pfizer spokesperson said the companies may later disclose vaccine efficacy from the trial but there have not been enough cases of Covid-19 yet among the participants to make that determination.
The vaccine was around 95 per cent effective in the adult clinical trial, but Pfizer has said that immunity wanes some months after the second dose. US regulators are expected to authorise a third, booster dose of the vaccine for older and high-risk Americans early this week.
The companies said the vaccine was well-tolerated, with side effects generally comparable to those observed in participants 16 to 25 years of age.
The Pfizer/BioNTech vaccine is one of three shots authorised in the United States, along with Moderna's two-dose vaccine and Johnson and Johnson's one-dose shot. The Moderna and J&J shots have not yet received full FDA approval for any age groups.
Both the Pfizer and Moderna vaccines have been linked by regulators to rare cases of heart inflammation in adolescents and young adults, particularly young men. Pfizer said they did not see any instances of heart inflammation in the trial participants.
